Senior Congress leader and former Punjab Chief Minister Amarinder Singh today disapproved of demands by some Sikh groups for UN intervention into 1984 Operation Blue Star, wondering what an international agency will do about the "old incident" about which "everything is known".

"I do not know what international agencies are going to do here. This is a 30-year-old incident. It was 1984. What are they going to probe now. Everything is recorded. Everything is known," the Congress' Deputy Leader in Lok Sabha told reporters outside Parliament.

Replying to questions about some Sikh group's demand for UN intervention, which has been opposed by Akalis, the Amritsar MP said, "They know about the military, CRPF and BSF intervention. They know about what was happening prior to Blue Star. What any international agency is going to probe into."

The 30th anniversary of Operation Blue Star was observed today at Akal Takht at the marbled periphery of Harmandhar Sahib popularly known as Golden Temple.

The operation was carried out on June 6, 1984 to flush out Sikh extremists led by Jarnail Singh Bhindranwale from the Golden Temple.

Bhindranwale and his associates were killed during Operation Blue Star.